/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.support.v4.widget;

import android.database.Cursor;
import android.widget.Filter;

/**
 * The CursorFilter delegates most of the work to the
 * {@link android.widget.CursorAdapter}. Subclasses should override these
 * delegate methods to run the queries and convert the results into String that
 * can be used by auto-completion widgets.
 */
class CursorFilter extends Filter {

	CursorFilterClient mClient;

	interface CursorFilterClient {
		CharSequence convertToString(Cursor cursor);

		Cursor runQueryOnBackgroundThread(CharSequence constraint);

		Cursor getCursor();

		void changeCursor(Cursor cursor);
	}

	CursorFilter(CursorFilterClient client) {
		mClient = client;
	}

	@Override
	public CharSequence convertResultToString(Object resultValue) {
		return mClient.convertToString((Cursor) resultValue);
	}

	@Override
	protected FilterResults performFiltering(CharSequence constraint) {
		Cursor cursor = mClient.runQueryOnBackgroundThread(constraint);

		FilterResults results = new FilterResults();
		if (cursor != null) {
			results.count = cursor.getCount();
			results.values = cursor;
		} else {
			results.count = 0;
			results.values = null;
		}
		return results;
	}

	@Override
	protected void publishResults(CharSequence constraint, FilterResults results) {
		Cursor oldCursor = mClient.getCursor();

		if (results.values != null && results.values != oldCursor) {
			mClient.changeCursor((Cursor) results.values);
		}
	}
}
